Fedora 15: Netgear WG111v2 gets very slow after a short amount of time

Question

Under Fedora 15, my Netgear WG111v2 (USB) adapter connects fine to my AP, allows normal download rates of about 800 kbps for about 20 seconds and then drops down to about 100kbps. What's the cause of this and how can I change it to normal behaviour? A rate of 800kbps is normal under Windows. Interestingly, there's some output of cfg80211 in dmesg (see below).

Output of iwconfig wlan0:

wlan0     IEEE 802.11bg  ESSID:"xxx"  
      Mode:Managed  Frequency:2.457 GHz  Access Point: xx:xx:xx:xx:xx:xx   
      Bit Rate=54 Mb/s   Tx-Power=20 dBm   
      Retry  long limit:7   RTS thr:off   Fragment thr:off
      Power Management:off
      Link Quality=48/70  Signal level=-62 dBm  
      Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
      Tx excessive retries:0  Invalid misc:74139   Missed beacon:0

dmesg:

[19860.248887] cfg80211: World regulatory domain updated:
[19860.248890] cfg80211:     (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[19860.248893] cfg80211:     (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[19860.248895] cfg80211:     (2457000 KHz - 2482000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
[19860.248897] cfg80211:     (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
[19860.248899] cfg80211:     (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[19860.248901] cfg80211:     (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[19860.248911] cfg80211: Calling CRDA for country: AT
[19860.252536] cfg80211: Regulatory domain changed to country: AT
[19860.252539] cfg80211:     (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[19860.252543] cfg80211:     (2402000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[19860.252545] cfg80211:     (5170000 KHz - 5250000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[19860.252548] cfg80211:     (5250000 KHz - 5330000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[19860.252551] cfg80211:     (5490000 KHz - 5710000 KHz @ 40000 KHz), (N/A, 2700 mBm)
[19861.857688] wlan0: authenticate with xx:xx:xx:xx:xx:xx (try 1)
[19861.859561] wlan0: authenticated
[19861.967688] wlan0: associate with xx:xx:xx:xx:xx:xx  (try 1)
[19861.969696] wlan0: RX ReassocResp from xx:xx:xx:xx:xx:xx  (capab=0x431 status=0 aid=2)
[19861.969699] wlan0: associated

Answer 1

Typically this slow down is that your wireless adapter Tx power is too high. The AP then turns down its Rx sensitivity and you realize it as a slow-down.